Book Information: Attack, the

The Animorphs have met the Elimist. He "helped" to save the kids when they were about to be eaten by a Taxxon. He "helped" to free two Hork-Bajir and restored Tobias' morphing ability. But, even though the Elimist has enormous power, he is not all-powerful. He has an enemy, the Crayak.

So, the Crayak and the Elimist decide that a battle will prove their ultimate power. But they don't intend to fight each other: The Elimist will choose the Animorphs and the Crayak will choose his own army. If the Animorphs lose they will be erased from the universe altogether. And there'll be no one left to fight the Yeerks....